Work is continuing on the study of the possible functions of cell sequences homologous to SV40 viral sequences. In particular, we have found that the interspersed highly repetitive DNA consists of nucleoside stretches of about 265 base pairs, showing strong homology with one another, and showing some homology with the origin of replication to both the viruses. These DNA sequences act as templates in vitro for polymerase II transcription and we are currently examining the RNA's produced in vivo that are homologous to these sequences and testing whether they also serve some role in initiation and replication of DNA.